The general objective of this project is to study physiological and behavioral correlates of tolerance to and dependence on alcohol in monkeys and rats. Specifically some studies are designed to examine the relationship between brain evoked potentials, operant behavior and blood alcohol levels. These measures will be used with acute and chronic alcohol administratio to study the time characteristics of tolerance to alcohol. Other experiments are designed to investigate the persistence of brain hyperexcitability subsequent to varying lengths ofexposure to alcohol. Studies are also proposed to examine the relation of withdrawal signs to maintenance and termination of alcohol self-administration. The relationship between tolerance and physical dependence will also be investigated.